Correcting typewriters utilizing adhesive correction media have been available in significant numbers since 1973 in the commercial marketplace. The previous correction tape constituted a reel to reel arrangement where each reel, takeup and supply were separate and independent and not commonly supported.
With the increased usage of ribbons in cartridges, it has become desirable to include the correction tape in a cartridge for ease in handling and ease in installation. By including the correction tape in the cartridge, it is also considerably easier to design a ribbon and correction tape feed mechanism to accommodate the cartridge than to have to accommodate a ribbon cartridge and separate and loose correction tape spools. With the inclusion of the correction tape within a correction tape cartridge, the physical volume occupied by the completely filled takeup spool becomes a consideration and, in many cases, a limiting consideration as to the quantity of tape that may be originally placed in the cartridge and the ability to consume all of the correction tape supplied.
One complicating factor when dealing with correction tapes generally not found when dealing with such things as film ribbons and fabric ribbons is that film and fabric ribbons will slip with respect to each other in a particular convolution while the tacky surface of the correction tape does not readily slip in the same manner. This non-slip nature of the correction tape resists normal smoothing of the takeup convolutions as may be accomplished with ribbons by tension. Therefore, once the material has become adhered to the adjacent backing, it is virtually impossible to cause a slipping by means of tension only.
As a result, any wrinkle inadvertently formed will propogate throughout the remainder of the radius of the takeup spool with additional convolutions.
Tensioning devices have been disclosed in the past which engage the periphery of ribbon spools. The most pertinent example of a tensioning device engaging the periphery of a takeup spool is found in U.S. Pat. No. 4,013,160. A second version of that device is illustrated in U.S. Pat. No. 4,147,439. In both cases, the ends of the spring member which constitutes a drag force on the supply spool has a second end engaged with the periphery of the takeup spool for purposes of forming a bias force between the two spools. The patents indicate that the function and purpose is that of providing a tension to the web and that a relatively high friction surface material is attached to the arm engaged with the supply spool to that end. Also, the braking surface is formed such that if a bulge is present, the action of the bulge against the brake will cause the brake to cam out and allow passage of the bulge.
This device, although providing the desired tension, does not appear to have any beneficial effect as far as maintaining a well ordered takeup spool inasmuch as the ribbon being transmitted will slip with respect to the next convolution and, therefore, does not present the problem encountered in the takeup spool portion of the correction tape cartridge disclosed in this application.